Surface-decorated foam skin of cross-linked rubbery soft olefin resin

ABSTRACT

A surface decorated foam skin of cross-linked rubbery soft olefin resin, comprising rubbery soft olefin resin, characterizing by having 
     (1) an average cell diameter of 50 to 400 μm, 
     (2) a crystallinity of 5 to 40% 
     (3) a hysteresis loss of 35% or lower, and 
     (4) an embossing percentage of 40% or higher.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a foam skin of cross-linked rubberysoft olefin resin whose surface is decorated likely as a leather or acloth having silver like tone, that is, the surface of which isdecorated using a mold which has embossed pattern or network pattern.More in detail relates to the rubbery olefin type cross-linked foam withsoft resin surface layer having good heat resistance, soft touch andrubbery elasticity.

DESCRIPTION OF PRIOR ART

In general, the foam whose surface is decorated was existent. Among theolefin type foam, polyethylene foam can be decorated by an embossed typemold. However, the surface layer of surface part is melted,re-solidified and becomes fine (because it is high crystalline typeresin). And the feeling of it is dry and rough and it is difficult toobtain a feeling of leather like or cloth like. To provide a finer anddeeper embossed pattern on the surface, it is necessary to intensify theheat melting condition of the surface, however, since the heatresistance of it is low (because the melting point of polyethylene islow, 100 to 120° C.), shrinking ratio by heating is big and theembossing by good dimensional stability is impossible.

The foam composed by a copolymer of ethylene.vinyl acetate have a littlesoftness, however, the heat resistance of it is inferior to that ofpolyethylene foam, and has a tendency to be hardened by the heating ofemboss processing. Therefore, said foam is not a suited material toprovide a fine and deep emboss pattern on it.

Polypropylene type foam has a good heat resistance, and therefore has amerit that the ordinary type of molding technique can be applied.However, it is a hard material, and when the surface is decorated, thesurface becomes too fine and the impression of hard is emphasized.

And if the surface of said kinds of foams whose surface is decorated areheated to the temperature higher than the melting point to improve thetranscribed ratio of grained pattern at the emboss processing, it loosesit's cushion feeling and becomes creased when it is bent, and is farfrom the feeling of leather like or cloth like, because the viscosity ofthese materials falls down suddenly and the permanent deformation offoam layer under the decorated surface becomes big at the embossprocessing (pressed),

As mentioned above, the olefin foam whose surface is decorated wasdeveloped and on the market, however the applications of it are forexample, a surface material of mold for an engineering works or insidematerials for waterproof sheet, and cannot be used as the surfacematerials for interior decorations.

Meanwhile, as olefin type foam which has soft touch and rubberyelasticity, an olefin type rubber foam which uses EPR or EPT as astarting materials can be mentioned, which has a good feeling as a foam.However, since this rubber foam is rubber foam which has rubberelasticity caused by a bridged material of non-crystalline rubbermolecular, is a very difficult materials for surface decoration(embossing) processing. Further, since the shrinking ratio of it byheating is high, the productivity as the materials of surface sheet in acase of after decoration of foam, and is a problem.

Rubber foams except olefin type, especially in a case of chloroprenerubber foam which has excellent soft feeling, besides the ordinaryproblems which EPR or EPT foams have, chlorine type toxic gas generatesat the heating of after decoration process, which is a seriousenvironmental problem for the corrosion of a equipment and for a humanbody.

As the method to solve these mentioned problems and to obtain a surfacedecorated olefin type foam which has good heat resistance, softness andrubbery elasticity, methods disclosed in Japanese Patent Laid OpenPublication 57-20334 or in Japanese Patent Laid Open Publication2-258247 are well-known. These methods are the method to decorate thesurface by laminating a heat plastic elastomer sheet having good heatresistance, softness and rubbery elasticity on above-mentioned foams.Therefore, in these methods, plural kinds of materials such as foam,surface layer sheet and adhesive are required at need, and themanufacturing process is complicated.

Meanwhile, the method disclosed in Japanese Patent Laid Open Publication6-278220 is the method to perform a specific grained pattern directly onsoft rubber foam by heating the sliced surface of rubber foam whose basematerial is high crystalline rubber using heat roller. This method isapplying the deflecting agglutination feature at hot working of highcrystalline rubber and therefore the surface grained pattern is special,however, has problems at surface toughness and heat resistance.

OBJECT OF THE INVENTION

This invention solves the problems accompany to the prior art, and theobject of this invention is to provide a new foam material which can bedecorated and can be used as an interior finishing material. Thismaterial not only has a good heat resistance, softness and rubberyelasticity, but also the surface of which has good heat treatmentprocessability, and the object of this invention is to provide a surfacedecorated rubbery soft olefin resin cross-linked foam like surfacelayer.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a material to be used as a material forsurface layer by an emboss process. Said material is rubbery and alsohas property of plastics (thermo-plastic), and uses properlycross-linked olefin type resin foam.

The important point of this invention is that a surface decorated foamskin of cross-linked rubbery soft olefin resin, comprising rubbery softolefin resin, characterizing by having average cell diameter of 50 to400 μm, a degree of crystallinity of 5 to 40% and a hysteresis loss of35% or lower. Further, said surface decorated foam skin of cross-linkedrubbery soft olefin resin is desirably characterized as the gel fractionis in the region of 20 to 98%, 50% compressive stress is in the regionof 0.3 to 1.5 kg/cm², 90° C. hot dimensional shrinking ratio is smallerthan 5%, and the transcribed ratio of grained pattern is smaller than40%.

That is, the average cell size of the foam like surface layer composedby rubbery soft olefin resin of this invention is 50 to 400 μm,desirably 50 to 200 μm, degree of crystallinity is 5 to 40%, desirably 5to 35%. When the degree of crystallinity is in this region, the foamlike surface layer of this invention shows sufficient restorability,good at decorative processing and generates elastic cushioning property.And by making hysteresis loss smaller than 35%, desirably smaller than30%, and further by making the transcribed ratio of grained patternsmaller than 40%, it becomes possible to provide the surface decoratedrubbery soft olefin resin cross-linked foam like surface layer which canbe easily decorated by surface heat treatment of a foam maintaining goodheat resistance, without spoiling softness and rubbery elasticity.

DETAILED DESCRIPTION OF THE INVENTION

Details of the invention are illustrated as follows.

As the rubbery soft olefin resin which composes this cross-linked foam,olefin type copolymer rubber or the mixture of crystalline polyolefinresin and olefin type copolymer rubber can be used.

Said mixture of crystalline polyolefin resin and olefin type copolymerrubber has a good rubbery elasticity, and when the mixture is used asthe rubbery soft olefin resin, the rubbery soft olefin resincross-linked foam like surface layer which generates excellentrestorability by rubbery elasticity can be obtained at each moldingprocess.

The olefin type copolymer rubber of this invention is an amorphouselastic copolymer whose contents of α-olefin of carbon number 2 to 20 issmaller than 50 mol % or an elastic copolymer whose degree ofcrystallinity is smaller than 50%, that is, non conjugated copolymer bynon crystalline α-olefin composed by more than two kinds of α-olefin,and more than two kinds of α-olefin.

As a concrete example of such kind of olefin type copolymer rubber,following kinds of rubber can be mentioned.

(1) Ethylene.α-olefin copolymer rubber

(2) Ethylene.α-olefin.non-conjugated copolymer rubber

(3) Propylene.α-olefin copolymer rubber

(4) Butene.α-olefin copolymer rubber

As the concrete example of above mentioned α-olefin, ethylene,propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 1-desene,1-undesene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene,1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosane,3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene,4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene,4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene,11-methyl-1-dodecene, 12-ethyl-1-tetradecene and combinations of thesecomponents can be mentioned.

As the concrete example of said non-conjugated diene, dicyclopentadiene,1,4-hexadiene, cyclooctadiene, methylenenorbornene andethylidenenorbornene can be mentioned.

Mooney viscosity [ML1.4(100° C.)] of these copolymer rubber is 10˜250,desirably is 40 to 150.

Iodine number of said (2) ethylene.α-olefin.non-conjugated copolymerrubber is desirably smaller than 25.

Above mentioned olefin type copolymer rubber can exist in non foamedrubbery soft olefin resin composed by the mixture of olefin typecopolymer rubber and crystalline polyolefin resin, by any possiblestates, e.g. non cross-linked, partially cross-linked or fullycross-linked.

Besides above mentioned olefin type copolymer rubber used in thisinvention, diene type rubber such as styrene-butadiene rubber (SBR),nitrile rubber (NBR), natural rubber (NR), butyl rubber (IIR), SEBS andpolyisobutylene can be used.

In the mixture of olefin type copolymer rubber and crystallinepolyolefin resin used in this invention, the desirable proportion ofolefin type copolymer rubber to be used is bigger than 30 parts andsmaller than 100 parts to 100 total parts of olefin type copolymerrubber and crystalline polyolefin resin by weight, more desirably from50 to 100 weight parts and further desirably 65˜95 weight parts.

As the crystalline polyolefin resin, α-olefin mono polymer or copolymerof carbon number 2 to 20 can be mentioned.

As the concrete example of said crystalline polyolefin resin, following(co) polymer can be mentioned.

(1) Ethylene mono polymer [polymer produced by-both low pressure methodand high pressure method can be used]

(2) Copolymer of ethylene with smaller than 10 mole % of other α-olefinor vinyl monomer such as vinyl acetate or ethyl acrylate.

(3) Propylene mono polymer.

(4) Random copolymer of propylene with smaller than 10 mole % of otherα-olefin.

(5) Block copolymer of propylene and smaller than 30 mole % of otherα-olefin.

(6) 1-butene mono polymer.

(7) Random copolymer of 1-butene mono polymer and smaller than 30 mole %of other α-olefin.

(8) 4-methyl-1-pentene mono polymer.

(9) Random copolymer of 4-methyl-1-pentene and smaller than 30 mole % ofother α-olefin.

As a concrete example of above mentioned α-olefin composing said sameα-olefin as to afore mentioned α-olefin type copolymer can be mentioned.

In the mixture of olefin type copolymer rubber and crystallinepolyolefin resin used in this invention, the desirable proportion ofcrystalline polyolefin resin is smaller than 70 weight parts to 100total weight parts of olefin type copolymer rubber and crystallinepolyolefin resin, more desirably smaller than 50 weight parts andfurther desirably 5 to 35 weight parts.

As a reformer of said mixture of olefin type copolymer rubber andcrystalline polyolefin resin, styrene.butadiene rubber, polybutadienerubber, polyisoprene rubber or hydrogenated type rubber of these rubberand chlorinated polyethylene can be added by the proportion smaller than10 weight % to 100 total weight % of olefin type copolymer rubber andcrystalline polyolefin resin.

As a softener used for this mixture, paraffin type, naphthene type oraromatic type softener or an ester type plasticizer can be added by theproportion smaller than 10 weight % to 100 total weight % of olefin typecopolymer rubber and crystalline polyolefin resin.

As mentioned above, since the foam of this invention is the cross-linkedfoam of rubbery soft olefin resin, generally a cell forming agent and across-linking agent are blended.

Meanwhile, when the cross-linking reaction of resin is made by theexposure of an ionizing radiation such as electron beam, neutron beam,α-rays, β-rays, γ-rays, X-rays or ultraviolet rays, it is not necessaryto blend the cross-linking agent. However, at the cross-linking reactionby the exposure of an ionizing radiation, a multi functionalmethacrylate monomer such as divinylbenzene, triallylcyanurate,ethyleneglycol dimethacrylate, trimethylolpropane trimethacrylate oracrylicmethacrylate, or a multi functional vinyl monomer such asvinylbutylate or vinylstearate can be added as a cross linking promoter.By blending said cross-linking promoter, gel fraction can be adjusted.

As the cell-forming agent to be used in this invention, a heatdecomposing type cell forming agent which generates gas by heatdecomposition is desirably used. As the concrete example,diethylazocarbonamide, azodicarbonamide, barium azodicarboxylate,4,4-oxybis(benzenesulfonylhydrazide),3,3-disulfonehydrazidephenylsulfonic acid and N,N-dinitropentatetraminecan be mentioned.

Ordinary, the cell forming agent is added by the proportion of 3 to 25weight parts to 100 weight part of the matrix of unformed rubbery softolefin resin, desirable proportion to be added is 5 to 20 weight partsand more desirable proportion to be added is 7 to 15 weight parts.

These cell forming agents can be used alone or by the combination ofmore than two types, further so called decomposing promoting agent canbe used together with.

Further, the cell of resin foam can be generated by the vapor pressureof volatile solvent or water, instead of cell forming by thecell-forming agent.

The cross-linking reaction of this invention can be carried out by thewell-known cross-linking method. As the typical example which usescross-linking agent, a cross-linking by vulcanization and across-linking by peroxide can be mentioned.

And also the cross-linking by ionizing radiation can be carried out bythe well-known cross-linking method.

The desirable cross-linking agent to be used in the method by peroxideis organic peroxide, and as the concrete example,

dicumylperoxide,

di-tert-butylperoxide,

2,5-dimethyl-2,5-di(tert-butylperoxy)hexane,

2,5-dimethyl-2,5-di(tert-butylperoxy)hexine-3,

1,3-bis(tert-butylperoxyisopropyle)benzene,

1,1-bis(tert-butylperoxy)-3,3,5-trimethylsyclohexane,

n-butyl-4,4-bis(tert-butylperoxy)valeriate,

benzoylperoxide,

p-chlorbenzoylperoxide,

2,4-dichlorobenzoylperoxide,

tert-butylperoxybenzoate,

tert-butyloxyisopropylecarbonate,

diacetylperoxide, lauroilperoxide and

tert-butylcumylperoxide can be mentioned.

Among these compounds,

2,5-dimethyl-2,5-di(tert-butylperoxy)hexane,

2,5-dimethyl-2,5-di(tert-butylperoxy)hexine-3,

1,3-bis(tert-butylperoxyisopropyl)benzene,

1,1-bis(tert-butylperoxy)-3,3,5-trimethylsyclohexane and

n-butyl-4,4-bis(tert-butylperoxy)valeriate can be desirably used fromthe view point of bad odor and scorching stability, and

1,3-bis(tert-butylperoxyisopropyl)benzene is most desirably used.

The desirable blending ratio of organic peroxide is 0.5 to 2.5 weightparts to 100 weight parts of un-foamed rubbery soft olefin resin matrix,and the substantial blending ratio is determined concerning cell size offoam, gel fraction and density.

In the present invention, as the cross-linking process by said peroxide,peroxy cross-linking promoting agent such as sulfur, p-quinonedioxime,p,p′-benzoylquinonedioxime, N-methyl-N-4-dinitrosoaniline,nitrosobenzene, diphenylguanidine, trimethylolpropane orN,N′-m-phenylenedimaleimide, or a multi-functional methacrylate monomersuch as divinylbenzene, trialylcyanu rate, ethyleneglycoldimethacrylate, trimethylolpropane, trimethacrylate oracrylicmethacrylate, or a multi functional vinyl monomer such asvinylbutylate or vinylstearate can be blended.

By blending of said cross-linking promoter, gel fraction can beadjusted.

To the rubbery soft olefin resin of this invention, additives which areordinary used to the olefin type thermo-plastic elastomer compositionsuch as cross-linking agent, cross-linking promoter, cell formingpromoter, weather resistance stabilizer, heat resistance stabilizer,plasticizer, fire retardant, viscosity increasing agent, slipping agent,and pigments can be added at need within the limit not to hurt theobject of this invention.

Furthermore, filler can be blended to said rubbery soft olefin resin canbe added. As the concrete example of the filler, an organic filler suchas carbon black, nitroso pigment, colcothar, phthalocyanine pigment,pulp, fiber like chip or agar-agar and an inorganic filler such as clay,kaoline, silica, diatomaceous earth, aluminum hydroxide, zinc oxide,magnesium hydroxide, titanium oxide, mica, bentonite, sirasu balloon,zeolite, silicate white earth, cement, and silica fume can be mentioned.

The cross-linked foam like surface layer of rubbery soft olefin resin.

Said foam like surface of this invention is a cross-linked foam ofrubbery soft olefin resin composed by above mentioned components, anddesirable cell size of it is 50 μm to 400 μm and more desirably 50 μm to200 μm.

The degree of crystallinity determined by an X-ray diffraction method ofthe mixture of polyolefin resin and rubber composing said foam likesurface layer of this invention which is prepared as mentioned above isdesirably to be within the region of 5 to 35% and more desirably 6 to25%.

Further, the hysteresis loss of the cross-linked foam of rubbery softolefin resin which composes the foam like surface layer of thisinvention prepared as above is desirably smaller than 35%, moredesirably smaller than 30%.

When the cell size, degree of crystallinity and hysteresis loss of thecross-linked foam like surface layer of rubbery soft olefin resin arewithin the region mentioned above, the heat treatment processability offoam like surface layer is very good and has good heat resistance andcan generate a softness and a rubber elasticity. In the meanwhile, themethod to measure the cell size, degree of crystallinity by X-raydiffraction method and hysteresis loss is disclosed in Example of thisinvention.

Additionally, the gel fraction of the cross-linked foam like surfacelayer of rubbery soft olefin resin is 20 to 98% and desirably 40 to 90%.When the gel fraction is within the above-mentioned limit, the heattreatment processability of foam like surface layer is very good and hasgood heat resistance and can generate softness and rubber elasticity.

Further, the 50% compressive stress of the cross-linked foam likesurface layer of rubbery soft olefin resin of this invention is 0.3 to1.5 kg/cm² and desirably 0.3 to 1.0 kg/cm², furthermore, the 90° C. hotdimensional shrinking ratio is smaller than 5% and desirably smallerthan 3%. When the 50% compressive stress and 90° C. hot dimensionalshrinking ratio are within the above mentioned limit, the heat treatmentprocessability of foam like surface layer is very good and has good heatresistance and can generate a softness and a rubber elasticity.

The method for preparation of the cross-linked foam like surface layerof rubbery soft olefin resin.

The cross-linked foam like surface layer of rubbery soft olefin resin ofthis invention can be prepared by the following method.

As the first step, all components mentioned above are kneadedhomogeneously and non-foamed non cross-linked rubbery soft olefin resinis prepared and the resin is molded to a desired shape.

As the method to prepare non foamed non cross-linked rubbery soft olefinresin, for example, the method to fuse and knead a heat decompositiontype cell forming agent, a cross-linking agent and other additivesseparately into the mixture (matrix) composed by olefin type copolymerrubber and crystalline polyolefin resin or olefin type copolymer rubber(matrix) can be mentioned.

In this method, for instance, olefin type copolymer resin andcrystalline polyolefin resin are kneaded by a well-known kneader such asV type brabender, tumble brabender, ribbon brabender, Henshel brabenderand further kneaded by an extruder, mixing roller, kneaded or Bumbury'smixer.

This kneading process is desirably to be carried out at the temperaturelower than decomposing temperature of the heat-decomposing cell formingagent.

The cell forming promoter, wetting agent, weather resistance stabilizer,heat-resistance stabilizer, anti-aging agent and pigments can be blendedat any melting kneading process.

Then, to the kneaded product obtained by mentioned kneading process, across-linking agent and cross-linking promoting agent and avulcanization promoting agent are added and kneaded by a well-knownkneader such as V type brabender, turnble brabender, ribbon brabender,Henshel brabender at desirably lower temperature than decomposingtemperature of cross-linking agent (50° C.), then the kneaded product isadded to a conventional well-known kneader such as open type mixingroller, not-open type Bumbury's mixer, extruder, kneader or continuousmixer and said cross-linking agent and other agents are dispersed.

Said kneading process is carried out at the lower temperature than thedecomposition temperature of a heat decomposing type cell forming agentand a cross-linking agent, and desirable temperature is 20 to 50° C.lower temperature than one minute half-time temperature of thecross-linking agent.

As the another preparing method of non foamed non cross-linked rubberysoft olefin resin, the method to add a heat decomposing cell formingagent, a cross-linking agent and other additives simultaneously toolefin type copolymer rubber and crystalline polyolefin resin and tomelt and knead can be mentioned.

In above mentioned method, olefin type copolymer rubber, pellets ofcrystalline polcrystalline polyolefin resin, and additives such as heatdecomposing cell forming agent and cross-linking agent are continuouslykneaded at lower temperature than the decomposing temperature of theheat decomposing cell forming agent and cross-linking agent using forexample double shaft extruder.

Then, the obtained non-foamed non cross-linked rubbery soft olefin resinis formed to a sheet shape at the temperature which the heat decomposingcell forming agent and cross-linking agent does not decompose, and noncross-linked, non-foamed sheet type product can be obtained.

Said forming can be carried out by conventional well-known formingmachine such as heat press or calendar roll.

Further, in the present invention, melting and kneading of olefin typecopolymer rubber and crystalline polyolefin resin, melting and kneadingof obtained mixture with a heat decomposing cell forming agent and across-linking agent and a procedure to obtain non cross-linked,non-foamed soft resin, can be carried out by series using a moldingmachine such as single shaft extruder or double shaft extruder.

The foam like surface layer of rubbery soft olefin resin can be obtainedby processing said formed product of non cross-linked, non-foamed softresin obtained by above-mentioned procedure. The formed sheet isprovided to a continuous heat double press belt which has specific sameheight brims on both width end or stuffed into a specific mold, heatpressed at higher temperature than 130° C. (desirably 140° C. to 230°C.) and higher pressure than 40 kg/cm² (desirably 60 kg/cm² to 150kg/cm²) for fixed time and then release the pressure, or after the heatpressure the un-foamed or the half foamed imperfect foam is secondaryfoamed at atmosphere pressure, thus the foam like surface layer ofrubbery soft olefin resin can be obtained.

In a case of foaming at atmosphere pressure, un-foamed product is heatedby a conventional well-known method such as hot air circulating, saltbath heating, radio-frequency heating, infra red rays heating and heatpress and a cross-linking agent and heat decomposing foaming agentcontained in un-foamed product are decomposed by heat, thus the foamlike surface layer of rubbery soft olefin resin of this invention can beobtained.

Among the above mentioned preparation method, the most desirable methodis mentioned as follows. That is, the heat pressure is made for fixedtime then release the pressure and obtain the foam like surface layer ofrubbery soft olefin resin of this invention directly, or the un-foamedor the half foamed imperfect foam is secondary foamed at atmospherepressure, and obtain the cross-linked foam like surface layer of rubberysoft olefin resin.

At the above-mentioned foaming process or just after the foaming, thespecific pattern can be provided on the surface of foam and further thesurface toughness can be improved by stamping of pattern.

The cross-linked foam like surface layer of rubbery soft olefin resin ofthis invention is composed by a rubbery soft olefin resin, and is thecross-linked foam like surface layer of rubbery soft olefin resin of

(1) average cell size is 50 μm to 400 mμ,

(2) degree of crystallinity of the foam is 5 to 40%,

(3) hystereresis loss is smaller than 35%, and

(4) gel fraction is 20 to 98%,

(5) 50% compressive stress is 0.3 to 1.5 kg/cm² and 90° C. hotdimensional shrinking ratio is 5 to 40%, has especially excellentprocessability of the surface of foam, has good heat resistance, hassoftness and rubber elasticity like fabrics or cloth and can obtain adecorated foam having an appearance of synthetic leather.

Concretely, as the heat treatment method of the foam surface, thesurface of foam obtained by above mentioned method, desirably thesurface of sliced foam is held and pressed between heat rollers or aheat press, or by a vacuum forming (concave mold) and the smoothness andthe toughness of the foam surface is remarkably improved. By engraving agrained pattern on the surface of roller, presser or a mold of vacuumforming (concave mold) and transcribe the pattern to the surface offoam, softness and rubbery elasticity can be generated on the surface offoam.

As the more desirable processing method of the foam surface, thefollowing method can be mentioned. That is, before the pressing byrollers or a presser or a vacuum forming, the surface of foam ispreviously heat treated by flame, infrared rays or hot air, then cold orhot pressed or formed by vacuum forming, and the surface of thecross-linked foam like surface layer of rubbery soft olefin resin isprocessed like a leather.

When a grained pattern or a network pattern is provided to the materialof this invention, even if the mold compressive ratio is closely to 10%the material is not crushed because it has a good restoration ability,and profound emboss like or cloth like pattern can be provided. Thisphenomenon cannot be expected to the conventional olefin type foam. Forexample, after the surface of a conventional polyethylene foam is heattreated, when compressive ratio at cold press is raised, the foam iscrushed remarkably and violently curled and good decorated foam cannotbe obtained.

These kinds of surface treatment process can be made continuously or bybatch processing. And the cross-linked foam like surface layer ofrubbery soft olefin resin on which the combination surface treatmentprocess with a coating or a printing is possible can be provided.

In the cross-linked foam like surface layer of rubbery soft olefin resinof this invention, the state of reverse side is not limited. The reverseside can be the foam itself or can be laminated to cloth, un-woven clothor sheet of thermo-plastic resin.

BRIEF ILLUSTRATION OF DRAWINGS

FIG. 1 is a drawing indicates a hysteresis curve to measure thehysteresis loss of the foam of this invention.

FIG. 2 is a mold used to measure the transcribed ratio of grainedpattern of the foam of this invention.

FIG. 3 is the schematic view of microscopic observation showingtranscript of grained pattern by use of the mold of FIG. 1

a shows the case of good transcript ratio.

b is the case showing that the transcript ratio is not good (showing thecase in which the foam is hard and edge is dulled, and in this caseW>W′)

c is the case showing that the transcript ratio is not good (showing thecase in which permanent deformation at the pressing process is big, andin this case H>H′)

b is the case showing that the transcript ratio is not good (showing thecase in which the foam shrinks by the influence of the preheating at thepressing process, and in this case P>P′ and W>W′)

EXAMPLES

The present invention is illustrated by the Examples, however, notintended to be limited to them.

In the Examples and Comparative Examples, density of a foam (g/cm³),average cell size (mm) and degree of crystallinity (%) are measured byfollowing methods.

<Measuring Method>

(1) density (g/cm³)

Specimen of 10 cm×10 cm square is cut from the sheet of foam ofthickness t(cm), and the weight (W[g]) of the specimen is weighted andthe density (g/cm³) is calculated by following numerical formula.

density (g/cm³)=W/(t×10×10)

(2) average cell size

Numbers of cells (n) per 3.3 mm square are counted by a microscope of 60magnification, and the average cell size (mm) is calculated by followingnumerical formula.

average cell size (mm)={square root over ( )}(3.3)/π·n

(3) degree of crystallinity

Measured by a wide-angle X-ray diffraction (signal intensity[CPS]. . .2θ[3°<2θ<40°]), total signal area belonging to crystalline is divided bytotal signal area belonging crystalline and amorphous state andexpressed by %. This value is indicated as the crystalline

(4) hysteresis loss (%)

Specimens of 5 cm×5 cm square are cut from the sheet of foam ofthickness t(cm), and the specimens are piled us and adjusted to 2.5 mmthickness and prepare a specimen for the measurement. Said preparedspecimen is pressed by 50 mm/min compressive speed at room temperatureusing a compression tester and the hysteresis at room temperature ismeasured. The compressive ratio is 50% to the original thickness. Theobtained hysteresis curve at above mentioned condition is recorded tothe recording paper is shown in FIG. 1, and the hysteresis loss ismeasured by following numerical formula.

hysteresis loss (%)=(i S1/S0)×100

wherein,

S1: area surrounded by curve B and curve D

S0: area surrounded by curve B, curve AE and Curve CE

(5) gel fraction (%)

A foam pad is cut to 1 mm square specimen chips, contained into aSoxhlet extractor and oil in specimen is extracted by chloroform. Thefoam pad specimen after extracted is dried up by vacuum and 0.2 g(W0[g]) of specimen is weighted. The weighted specimen is dissolved into500 ml of 130° C. heated xylene for 6 hours and xylene soluble parts areextracted from the specimen. The xylene insoluble part is rinsed byacetone and dried up in 100° C. vacuum dryer for 1 hour. After dried up,the xylene insoluble part is weighted (W1[g]) and gel fraction (%) iscalculated by following numerical formula.

gel fraction (%)=(W1/W0)×100

(6) 50% compressive hardness [kg/cm²]50% compressive hardness [kg/cm²]at 25° C. is measured in accordance with the measuring method ofJISK-6767.

(7) hot dimensional shrinking ratio (%) hot dimensional shrinking ratioat 90° C. is measured in accordance with the measuring method ofJISK-6767.

(8) transcribed ratio of grained pattern (%)

Grained pattern is transcribed over the surface of a foam using aconcave mold with 1.0 mm width (W), 1.0 mm depth (d), 2.0 mm pitch (p)grit pattern (groove) illustrated by FIG. 2. After processed, the foamis cut along with the grit mark and the height of grained pattern (H)and pitch (P) are observed by a microscope, and transcribe ratio ofgrained pattern (%) is calculated by following numerical formula.

transcribed ratio of grained pattern (%)=[height(H)+pitch(P)]×100/3

Substantial examples indicating several transcribed pattern are shown inFIG, 3.

Example 1

To 100 weight parts of the mixture composed by ethylene.propylene.non-conjugated copolymer rubber [EPT; 38 mol % propylene content. Iodinenumber 12, MFR (ASTM 1238, 190° C., 2.16 kg load) 1.1 g/10 min],polyethylene [PE; 100 mol % ethylene content, MFR (ASTM 1238, 190° C.,2.16 kg load) 1.6 g/10 min] and polypropylene [P; 100% propylenecontent, MFR (ASTM 1238, 190° C., 2.16 kg load) 5.0 g/10 min], whereinEPT:PE:PP is 6:2:1, 10 weight parts of azodicarbonamide [ADCA; cellforming agent], 1.2 weight parts of2,5-dimethyl-2,5-di(tert-dibutylperoxy) hexine-3 [peroxide cross-linkingagent] and 0.3 parts of trimethylolpropanetrimethacrylate [TMPT;cross-linkage promoting agent] are added and kneaded by a roller mixerand non-cross-linked, non-foamed composition is obtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 210° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.058 g/cm³ and thickness is 8.7 mm. This cross-linked foam skin is afoam of 80 μm average cell size, 8% degree of crystallinity, 20%hysteresis loss, 77.0% gel fraction, 650 g/cm² 50% compressive stressand 3.3% hot dimensional shrinking ratio at 90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved at compressive ratio 50%and 90%. The surface of the foam faced to the flat plate becomes smoothsurface with a skin layer, and to the surface of the foam faced to theplate with grained pattern the pattern is clearly transcribed(transcribed ratio of grained pattern, 91% and 96%). After the surfaceheat treatment, 50% compressive stress and hot dimensional shrinkingratio at 90° C., 22 hours are measured and the result of 600 g/cm² and1.1% can be obtained. Thus, the cross-linked foam like surface layer ofrubbery soft olefin resin with smooth and tough skin layer and grainedpattern whose heat resistance and softness is good can be obtained.

Example 2

To 100 weight parts of the mixture composed by 60 weight parts ofethylene.propylene.non-conjugated copolymer rubber [EPT], polyethylene[PE] and polypropylene [PP] of Example 1, wherein EPT:PE:PP is 6:2:1, 3weight parts of azodicarbonamide [ADCA; cell forming agent], 1.2 weightparts of 2,5-dimethyl-2,5-di(tert-dibutylperoxy) hexine-3 [peroxidecross-linking agent] and 0.3 parts of trimethylolpropanetrimethacrylate[TMPT; cross-linkage promoting agent] are added and kneaded by a doubleshaft kneading extruder at 120° C. and non-cross-linked, non-foamedcomposition is obtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 210° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.053 g/cm³ and thickness is 7.2 mm. This cross-linked foam skin is afoam of 95 μm average cell size, 8% degree of crystallinity, 22%hysteresis loss, 71.0% gel fraction, 980 g/cm² 50% compressive stressand 3.5% hot dimensional shrinking ratio at 90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved at the compressive ratio50% and 90%. The surface of the foam faced to the flat plate becomessmooth surface with a skin layer, and to the surface of the foam facedto the plate with grained pattern the pattern is clearly transcribed(transcribed ratio of grained pattern, 83% and 93%). After the surfaceheat treatment, 50% compressive stress and hot dimensional shrinkingratio at 90° C., 22 hours are measured and the result of 970 g/cm² and1.3% can be obtained. Thus, the cross-linked foam like surface layer ofrubbery soft olefin resin with smooth and tough skin layer and grainedpattern whose heat resistance and softness is good can be obtained

Example 3

To 100 weight parts of the mixture composed by 65 weight parts ofethylene.propylene.non-conjugated copolymer rubber [EPT] and 10 weight %of polypropylene [PP] of Example 1, 6 weight parts of azodicarbonamide[ADCA; cell forming agent], 0.7 weight parts of2,5-dimethyl-2,5-di(tert-dibutyl peroxy)hexine-3 [peroxide cross-linkingagent], 0.7 parts of trimethylolpropane-trimethacrylate [TMP;cross-linkage promoting agent] and 1.0 part of zinc oxide are added andkneaded by a roller mixer at 120° C. and non-cross-linked, non-foamedcomposition is obtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 165° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.047 g/cm³ and thickness is 8.7 mm. This cross-linked foam skin is afoam of 58 μm average cell size, 27% degree of crystallinity, 25%hysteresis loss, 65.0% gel fraction, 750 g/cm² 50% compressive stressand 2.5% hot dimensional shrinking ratio at 90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved at compressive ratio 50%and 90%. The surface of the foam faced to the flat plate becomes smoothsurface with a skin layer, and to the surface of the foam faced to theplate with grained pattern the pattern is clearly transcribed(transcribed ratio of grained pattern, 91% and 96%). After the surfaceheat treatment, 50% compressive stress and hot dimensional shrinkingratio at 90° C., 22 hours are measured and the result of 730 g/cm² and0.7% can be obtained. Thus, the cross-linked foam like surface layer ofrubbery soft olefin resin with smooth and tough skin layer and grainedpattern whose heat resistance and softness is good can be obtained

Example 4

To 100 weight parts of the mixture composed by 60 weight parts ofethylene.propylene.non-conjugated copolymer rubber [EPT], polyethylene[PE] and polypropylene [PP] of Example 1, wherein EPT:PE:PP is 6:1:2, 6weight parts of azodicarbonamide [ADCA; cell forming agent], 1.4 weightparts of 1,3bis(tert-butylperoxyisopropyle)benzene [peroxidecross-linking agent], 0.3 parts of trimethylolpropanetrimethacrylate[TMP; cross-linkage promoting agent], 0.5 weight parts stearic acid(slipping agent) and 1.0 part of zinc oxide are added and kneaded by aroller mixer at 1 20° C. and fed out as a sheet by a roller andnon-cross-linked, non-foamed composition is obtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 165° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.049 g/cm³ and thickness is 8.7 mm. This cross-linked foam skin is afoam of 64 μm average cell size, 16% degree of crystallinity, 21%hysteresis loss, 76.0% gel fraction, 690 g/cm² 50% compressive stressand 1.5% hot dimensional shrinking ratio at 90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved at compressive ratio 50%and 90%. The surface of the foam faced to the flat plate becomes smoothsurface with a skin layer, and to the surface of the foam faced to theplate with grained pattern the pattern is clearly transcribed(transcribed ratio of grained pattern, 86% and 93%). After the surfaceheat treatment, 50% compressive stress and hot dimensional shrinkingratio at 90° C., 22 hours are measured and the result of 660 g/cm² and0.9% can be obtained. Thus, the cross-linked foam like surface layer ofrubbery soft olefin resin with smooth and tough skin layer and grainedpattern whose heat resistance and softness is good can be obtained

Example 5

To 100 weight parts of the mixture composed of ethylene.propylene.non-conjugated copolymer rubber [EPT] and polypropylene [PP] of Example1, wherein EPT:PP is 6:3, 10 weight parts of azodicarbonamide [ADCA;cell forming agent], 0.8 weight parts of 1,3bis(tert-butylperoxyisopropyle)benzene [peroxide cross-linking agent], 0.8 parts oftrimethylolpropane-trimethacrylate [TMPT; cross-linkage promotingagent], 0.5 weight parts stearic acid and 1.0 part of zinc oxide areadded and kneaded by a roller mixer at 120° C. and fed out as a sheet bya roller and non-cross-linked, non-foamed composition is obtained.

Then, the resin composition is poured into the mold of 2 mm thicknessand heat pressed at 210° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.045 g/cm³ and thickness is 5 mm. This cross-linked foam skin is a foamof 110 μm average cell size, 21% degree of crystallinity, 20% hysteresisloss, 67.0% gel fraction, 740 g/cm² 50% compressive stress and 1.0% hotdimensional shrinking ratio at 90° C., 22 hours.

To the obtained sheet of cross-linked foam infrared rays is irradiated,then cold pressed between a flat plate and a plate on which grainedpattern is engraved at compressive ratio 50% and 90%. The surface of thefoam faced to the flat plate becomes smooth surface with a skin layer,and to the surface of the foam faced to the plate with grained patternthe pattern is clearly transcribed (transcribed ratio of grainedpattern, 94% and 96%). After the surface heat treatment, 50% compressivestress and hot dimensional shrinking ratio at 90° C., 22 hours aremeasured and the result of 710 g/cm² and 0.8% can be obtained. Thus, thecross-linked foam like surface layer of rubbery soft olefin resin withsmooth and tough skin layer and grained pattern whose heat resistanceand softness is good can be obtained

Comparative Example 1

To 100 weight parts of ethylene.propylene.non-conjugated copolymerrubber [EPT] of Example 1, 6 weight parts of azodicarbonamide [ADCA;cell forming agent], 1.2 weight parts of2,5-dimethyl-2,5-di(tert-dibutylperoxy)hexine-3 [peroxide cross-linkingagent], 0.3 parts of trimethylolpropane-trimethacrylate [TMPT;cross-linkage promoting agent], 0.5 weight parts stearic acid and 1.0part of zinc oxide are added and kneaded by a roller mixer at 120° C.and fed out as a sheet by a roller and non-cross-linked, non-foamedcomposition is obtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 165° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.070 g/cm³ and thickness is 8.3 mm. This cross-linked foam skin is afoam of 150 μm average cell size, 0% degree of crystallinity, 20%hysteresis loss, 90.0% gel fraction, 630 g/cm² 50% compressive stressand 5.3% hot dimensional shrinking ratio at 90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved by compressive ratio 50%and 90%. The surface of the foam faced to the flat plate is largelyshrunk and hardened and becomes coarse, and to the surface of the foamfaced to the plate with grained pattern the pattern the grained patternis not transcribed (transcribed ratio of grained pattern, 8% and 13%).And after the surface heat treatment, 50% compressive stress and hotdimensional shrinking ratio at 90° C., 22 hours are measured and theresult of 600 g/cm² and 6.1% can be obtained. Softness is good, however,the heat resistance is not good.

Comparative Example 2

To 100 weight polyethylene [PE] of Example 1, 6 weight parts ofazodicarbonamide [ADCA; cell forming agent], 0.8 weight parts of1,3bis(tert-butylperoxy isopropyle)benzene [peroxide cross-linkingagent], 0.5 weight parts stearic acid and 1.0 part of zinc oxide areadded and kneaded by a roller mixer at 120 °C. and fed out as a sheet bya roller and non-cross-linked, non-foamed composition is obtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 165° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.045 g/cm³ and thickness is 8.7 mm.

This cross-linked foam skin is a foam of 110 μm average cell size, 55%degree of crystallinity, 55% hysteresis loss, 78.0% gel fraction, 1500g/cm² 50% compressive stress and 7.3% hot dimensional shrinking ratio at90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved by compressive ratio 60%and 90%. The surface of the foam faced to the flat plate becomes smoothsurface with a skin layer, and to the surface of the foam faced to theplate with grained pattern the pattern seemed to be clearly transcribed,however, the transcribed ratio of grained pattern are 65% and 35%,because the shrinkage at heating process and permanent deformation atpressing process are big. After the surface heat treatment, 50%compressive stress and hot dimensional shrinking ratio at 90° C., 22hours are measured and the result of 1800 g/cm² and 5.1% can beobtained, and the softness and heat resistance are hurt. When thesurface with grained pattern is slightly fold to the inside, manycreases are generated and the appearance of decorated surface is hurt.

Comparative Example 3

To 100 weight parts of ethylene. vinyl acetate. copolymer [EVA; 14%vinyl acetate content, MFR (JISK-6703, 190° C., 2.16 kg load) 1.3/10min], 10 weight parts of azodicarbonamide [ADCA; cell forming agent],0.8 weight parts of 1,3bis(tert-butylperoxy isopropyle)benzene [peroxidecross-linking agent], 0.5 weight parts stearic acid and 1.0 part of zincoxide are added and kneaded by a roller mixer at 120° C. and fed out asa sheet by a roller and non-cross-linked, non-foamed composition isobtained.

Then, the resin composition is poured into the mold of 3 mm thicknessand heat pressed at 165° C., 100 kg/cm² as to carry out cross-linkingand foaming and obtained the sheet of cross-linked foam whose density is0.045 g/cm³ and thickness is 8.7 mm.

This cross-linked foam skin is a foam of 80 μm average cell size, 9%degree of crystallinity, 45% hysteresis loss, 93.0% gel fraction, 1100g/cm² 50% compressive stress and 8.5% hot dimensional shrinking ratio at90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved at compressive ratio 50%and 90%. The surface of the foam faced to the flat plate becomes smoothsurface with a skin layer, and to the surface of the foam faced to theplate with grained pattern the pattern is not clearly transcribed. Thetranscribed ratio of grained pattern are 15% and 25%, and are low level,because the diacetic acid reaction is progressed in a molecular andintermolecular cross-linking reaction is progresses at surface heatingprocess After the surface heat treatment, 50% compressive stress and hotdimensional shrinking ratio at 90° C., 22 hours are measured and theresult of 1500 g/cm² and 10.2% can be obtained, and the softness andheat resistance are spoiled. This product has residue of odor of aceticacid.

Comparative Example 4

To 100 weight parts of the mixture composed by 20 weight parts ofpolyethylene [PE] and 80 weight of polypropylene [PP] of Example 1, 10weight parts of azodicarbonamide [ADCA; cell forming agent], 5.0 weightparts of divinylbenzene [DVB; cross-linking promoting agent], are addedand kneaded by a double shaft kneading extruder and extruded as a sheetand non-cross-linked, non-foamed composition is obtained.

Then, to the resin composition sheet an electron beam of 6 Mrad isirradiated, and is cross-linked and foamed at atmosphere at 220° C., andthe sheet of cross-linked foam whose density is 0.07 g/cm³ and thicknessis 8.7 mm is obtained.

This cross-linked foam skin is a foam of 120 μm average cell size, 78%degree of crystallinity, 60% hysteresis loss, 64.0% gel fraction, 2100g/cm² 50% compressive stress and 1.3% hot dimensional shrinking ratio at90° C., 22 hours.

Obtained sheet of cross-linked foam are sliced to 3 mm thickness andinfrared rays is irradiated, then cold pressed between a flat plate anda plate on which grained pattern is engraved at compressive ratio 50%and 90%. The surface of the foam faced to the flat plate becomes smoothsurface with a skin layer, and to the surface of the foam faced to theplate with grained pattern the pattern is seemed to be clearlytranscribed, however, the transcribed ratio of grained pattern are low,64% and 43%, because after heating, the permanent deformation atpressing process are big. After the surface heat treatment, 50%compressive stress and hot dimensional shrinking ratio at 90° C., 22hours are measured and the result of 2300 g/cm² and 0.7% can beobtained. The heat resistance is good, however, softness is hurt.

The property of surface decorated foams mentioned in Examples 1 to 5 andComparative Examples 1 to 4 are summarized in Table 1 and Table 2.

TABLE 1 properties Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 foam cell size (μm) 8095 58 64 110 crystallinity (%) 8 8 27 16 21 hysteresis loss (%) 20 22 2521 20 gel fraction (%) 77 71 65 76 67 50% compressive 650 980 750 690740 hardness (g/cm²) dimensional shrinking 3.3 3.5 2.5 1.5 1.1 ratio (%)foam after 50% compressive 600 970 730 660 710 surface hardness (g/cm²)soft soft soft soft soft heat dimensional shrinking 1.1 1.3 0.7 0.9 0.8treated ratio (%) good good good good good surface smoothness good goodgood good good grained pattern good good good good good appearancegrained pattern transcribed ratio (%) 50% compressed 91 83 74 86 94 100%compressed 96 93 87 93 96

TABLE 2 Co. Co. Co. properties Co. Ex. 1 Ex. 2 Ex. 3 Ex. 4 foam cellsize (μm) 150 110 80 120 crystalline ratio (%) 0 55 9 78 hysteresis loss(%) 20 55 45 60 gel fraction (%) 90 78 93 64 50% compressive 630 15001100 2100 hardness (g/cm²) dimensional shrinking 5.3 7.3 8.5 1.3 ratio(%) foam 50% compressive 600 1800 1500 2300 after hardness (g/cm²) softhard hard hard surface dimensional shrinking 6.1 1.3 0.7 0.9 heat ratio(%) not not not good treated good good good surface smoothness not goodgood good good sharpness of not good good good good grained patterngrained pattern transcribe ratio (%) 50% compressed 8 65 15 64 90%compressed 13 35 25 43

From these Examples, the cross-linked foam like surface layer of rubberysoft olefin resin of this invention which is composed by a rubbery softolefin resin and has properties of average cell size is 50 μm to 400 mμ,degree of crystallinity of the foam is 5 to 40%, hystereresis loss issmaller than 35% and transcribed ratio of grained pattern is bigger than40%, has a good surface smoothness, an excellent surface heatprocessability, a good heat resistance and softness and rubberyelasticity. Further, the decorated foam which has a leather likeappearance can be obtained.

The Possibility For the Industrial Use

As mentioned above, the cross-linked foam like surface layer of thisinvention, the fine and silver like surface layer can be obtained byfoaming with skin and by transcribing the grained pattern and furtherthe surface intensity is improved. On the contrary, by formingtranscribed pattern and network on the sliced surface of foam, thesurface layer with grained pattern or cloth pattern with good feeling.And in any case, the rubbery soft olefin resin cross-linked foam likesurface layer is not creased and fine and deep pattern can be embossed,has good feeling and surface intensity can be improved. Thus the surfacelayer which is suited to the interior surface decoration can beprovided.

What is claimed is:
 1. A surface decorated foam skin of cross-linked rubbery soft olefin resin, comprising rubbery soft olefin resin, characterizing by having average cell diameter of 50 to 400 μm, a degree of crystallinity of 5 to 40% and a hysteresis loss of 35% or lower.
 2. The surface decorated foam skin of cross-linked rubbery soft olefin resin of claim 1, wherein the gel fraction of said rubbery soft olefin resin is 20 to 98%.
 3. The surface decorated foam skin of cross-linked rubbery soft olefin resin of claim 1, wherein the 50% compressive stress is 0.3 to 1.5 kg/cm² and 90% hot dimensional shrinking ratio is 5% or lower.
 4. The surface decorated foam skin of cross-linked rubbery soft olefin resin of claim 1, wherein the grained pattern transcribed ratio is 40% or higher. 